In water consuming household appliances, such as dishwashers and washing machines, the water consumption has decreased steadily during the last couple of years. In dishwashers the average water consumption has come down to approximately 10 liters per washing cycle. There is however an aim to reach even lower levels of water consumption. In this perspective, reusing partially the process water in a dishwasher or washing machine in a following washing cycle would be a way to achieve a significant improvement in the total water consumption. In past years a variety of solutions have been proposed. For example, in U.S. Pat. No. 5,606,878A it is described a clothes washing machine provided with a recovery tank to recover water that is discharged in one or more rinsing phases. The recovered water is then reused in the first washing or pre-washing phase in a subsequent washing cycle.
However, there are some typical problems associated with the storage of water containing at least some organic residues such as bad smell, tank fouling and hydraulic components clogging, bacteria proliferation and hygienic issues. In other proposed solutions these problems have been addressed with more or less advanced purification and/or disinfection treatments, e.g. filtration, UV or ozone treatments, for the reduction or prevention of the fouling problems.
In U.S. Pat. No. 5,307,650B a washing machine with a reservoir container for storing rinse water is disclosed. The reservoir container is provided with a germicide means which kills any bacteria or microbes that could be present in the water and inhibits further bacterial growth. The germicide means is described as being a lamp or a dispenser with germicidal fluid.
DE102008029908A discloses a water reservoir containing water that is used for different purposes in for example a dishwasher. Brine is introduced in the water reservoir for inhibition of germ and/or bacteria growth. The amount of the brine is regulated and/or controlled depending on the water quantity.
However, the described prior art arrangements for inhibiting bacteria growth in the water reservoir add complexity to the appliance. Another drawback is that an addition of a compound for inhibiting bacterial growth may have other unwanted side effects, such as affecting the goods to be cleaned, the user handling the appliance, the environment or the process in a sewage treatment plant.
Water scarcity is already a fact in several regions of the world and the ongoing climate change is most likely to aggravate the situation. Therefore, there is a need for improvements in household appliances for washing and rinsing goods to further reduce the water consumption.